30 OUR NATIVE FERNS AND THEIR ALLIES. 



side), and may be examined with a strong lens. The three di- 

 visions are summed up as follows : 



"I. Vernation wholly straight. B. simplex Hitch. (Fig. 31). 



II. Vernation partly inclined in one or both portions. B. 

 lunaria Swz. (Fig. 32), B. boreale Milde, B. neglectum Wood 

 (Fig. 33), and B. obliquum Michl (Fig. 34) and its allies. 



III. Vernation wholly inclined, in the fertile frond recurved. 

 B. lanceolatum Angs. (Fig. 35), a-nd B. Virginianum Swz." 



The special characters of each species will be found under 

 the descriptions of the Botrychia later in this work. The cuts 

 will be valuable for reference, and will enable even beginners to 

 identify the species of this complicated genus with compara- 

 tively little difficulty. 



84. Fructification. — In this order of plants 

 the fructification consists of sporangia, which_ 

 unlike those of the true ferns, are not reticulated, 

 possess no trace of a ring, open by a transverse 

 slit, and are variously spiked and panicled (Fig. 

 20). In the adder-tongues (Ophioglossum) the 

 sporangia are large, and cohere in two ranks 

 along the margins of a single spike, opening 

 transversely to discharge their copious sulphur- 

 yellow spores. In the grape-ferns (Botrychium) 

 the sporangia are globular and arranged in double 

 rows along the narrow segments, more or less in 

 panicles. In both genera the sporangia are not 

 developed from the epidermal cells, but arise 

 from a transformation of the interior tissue of the leaf. This, 

 with other characters as clearly defined, serves to separate these 

 anomalous plants from the families of true ferns. 



85. Germination. — Among the OphioglossacE/E, so far 

 as known, the prothallia are destitute of chlorophyll, develop 

 under ground, and are monoecious. In Botrychium lunaria 

 the prothallium is an ovoid mass of cellular tissue, light brown 

 without and yellowish white within. It produces a number of 

 antheridia and archegonia on the upper surface as well as the 

 lower, differing in a few minor points from the true ferns in the 

 method of their development. 



Fig. 20. — En- 

 larged sporangfia 

 of Boiryckium 

 Virginianum 

 Swz. 



